Solvent-regulated 3D PEI-PVBC polymer structuring on CF for enhanced interfacial performance of CFRPs

Carbon fiber-reinforced polymers (CFRPs), known for their excellent high specific strength, have become crucial materials in the development of modern high-performance industries. In this study, a mild and simple self-assembly strategy was implemented using polyethyleneimine (PEI) and poly(vinylbenzyl chloride) (PVBC) to construct a novel three-dimensional polymer macrostructure on carbon fibers (CFs). Such a configuration was achieved through a binary solvent system, comprising a good solvent and a poor solvent, which controlled the deposition morphology of PVBC chains. The interfacial strength and toughness of CFRPs were significantly improved without compromising fiber strength. Compared to composites reinforced with the pristine CF or those modified with traditional thin polymer coatings (CF-P-PVBC), the three-dimensional microstructured CF-P-PVBC-W composites exhibited significant improvements in interfacial shear strength (IFSS), interlaminar shear strength (ILSS), and impact toughness. Particularly, when the water-to-dichloromethane ratio was 2:1, the most pronounced enhancements in IFSS and ILSS were observed, reaching values of 101.75 MPa and 101.41 MPa, respectively. The proposed strategy offers a novel approach to enhance the interfacial adhesion of CFRPs via polymer modification.